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Principles of Bioinorganic Chemistry - 2004. Note: The course seminar presentations will be held on Sunday, October 31, 2004 beginning at 8:30 AMin the Bush Room. Please remember that daylight savings time ends that day. Protein Tuning of Metalloprotein Core Function. PRINCIPLES :.
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Principles of Bioinorganic Chemistry - 2004 Note: The course seminar presentations will be held on Sunday, October 31, 2004 beginning at 8:30 AMin the Bush Room. Please remember that daylight savings time ends that day.
Protein Tuning of Metalloprotein Core Function PRINCIPLES: • Similar groups perform different functions depending upon their environment • Changes in available coordination sites controls function • Redox potentials are tuned by the ligands; H-bonding, e • Substrate binding affects the timing of electron transfer • Substrate specificity dictated by a.a. side chains in active site • Multiple prosthetic groups can couple functions ILLUSTRATIONS: • Sulfite Oxidase • Nitrogenase • Cyt. c Oxidase • Rieske Proteins • Blue Copper • Iron-sulfur proteins • Cytochromes • Aconitase • Zinc Proteins
Axial Ligands in Porphyrins Control Function Replacement of the axial His by Met allows cytochrome c to function as a catalyst for H2O2 conversion of PhNMe2 to PhNHMe. Met easily displaced.
Aconitase:Replacement of the terminal ligand at a [4Fe-4S] cluster site allows catalysis of isocitrate to citrate.
Coupled Processes - Sulfite Oxidase If cleave the enzyme with a protease, can isolate the Mo domain (non-heme). It will still do its chemistry, but needs an oxidant like O2 or [Fe(CN)6 ]3-; it will not use cyt cox
Nitrogenase - The P Cluster reduced state oxidized state bridging bridging 6-coord. S
Cytochrome c Oxidase O2 binds and is reduced at the CuB-heme pair
Proposed O–O Bond Splitting Mechanism O–O bond splitting mechanism in cytochrome oxidase Margareta R. A. Blomberg, Per E. M. Siegbahn, Gerald T. Babcock and Mårten Wikström
5.062, 2004 Finé!